Delete files older than 3 months old in a directory using .NET

Something like this outta do it.

using System.IO; 

string[] files = Directory.GetFiles(dirName);

foreach (string file in files)
{
   FileInfo fi = new FileInfo(file);
   if (fi.LastAccessTime < DateTime.Now.AddMonths(-3))
      fi.Delete();
}

Here's a 1-liner lambda:

Directory.GetFiles(dirName)
         .Select(f => new FileInfo(f))
         .Where(f => f.LastAccessTime < DateTime.Now.AddMonths(-3))
         .ToList()
         .ForEach(f => f.Delete());

For those that like to over-use LINQ.

(from f in new DirectoryInfo("C:/Temp").GetFiles()
 where f.CreationTime < DateTime.Now.Subtract(TimeSpan.FromDays(90))
 select f
).ToList()
    .ForEach(f => f.Delete());

Here's a snippet of how to get the creation time of files in the directory and find those which have been created 3 months ago (90 days ago to be exact):

    DirectoryInfo source = new DirectoryInfo(sourceDirectoryPath);

    // Get info of each file into the directory
    foreach (FileInfo fi in source.GetFiles())
    {
        var creationTime = fi.CreationTime;

        if(creationTime < (DateTime.Now- new TimeSpan(90, 0, 0, 0)))
        {
            fi.Delete();
        }
    }

The most canonical approach when wanting to delete files over a certain duration is by using the file's LastWriteTime (Last time the file was modified):

Directory.GetFiles(dirName)
         .Select(f => new FileInfo(f))
         .Where(f => f.LastWriteTime < DateTime.Now.AddMonths(-3))
         .ToList()
         .ForEach(f => f.Delete());

(The above based on Uri's answer but with LastWriteTime.)

Whenever you hear people talking about deleting files older than a certain time frame (which is a pretty common activity), doing it based on the file's LastModifiedTime is almost always what they are looking for.

Alternatively, for very unusual circumstances you could use the below, but use these with caution as they come with caveats.

CreationTime
.Where(f => f.CreationTime < DateTime.Now.AddMonths(-3))

The time the file was created in the current location. However, be careful if the file was copied, it will be the time it was copied and CreationTime will be newer than the file's LastWriteTime.

LastAccessTime
.Where(f => f.LastAccessTime < DateTime.Now.AddMonths(-3))

If you want to delete the files based on the last time they were read you could use this but, there is no guarantee it will be updated as it can be disabled in NTFS. Check fsutil behavior query DisableLastAccess to see if it is on. Also under NTFS it may take up to an hour for the file's LastAccessTime to update after it was accessed.